Dash Cam Storage Calculator

How we research

A dash cam overwrites its oldest footage when the card is full, so the card size decides how much you can look back on. This calculator estimates how many hours a card holds from the bitrate of your cameras, and works out the card size for a number of hours you want to keep. It is an estimate, so check your camera’s own figures.

Last updated: 19 October 2026

Your card

Space you want to keep free or that your device does not show.

Front camera
Rear camera (optional)
Going the other way

How it works

The calculator multiplies the bitrate by the time to get the amount of data. One megabit per second for one hour is 3,600 megabits, which is 450 megabytes, so each Mbps uses 0.45 GB an hour. It adds the front and rear bitrates, then divides the usable card size by that figure. We count 1 GB as 1,000 MB.

A worked example

A 128 GB card with a front camera at 30 Mbps and a rear camera at 13.5 Mbps has a total of 43.5 Mbps. That is 43.5 × 0.45, about 19.6 GB an hour, so the card holds about 6.5 hours. To keep 24 hours at that bitrate you would need about 470 GB, which is more than the 128 GB maximum that Road Angel lists for its Halo Pro [2], so check your camera’s limit before you buy a card.

Illustrative scenario: figures are examples, not quotes, valuations or market prices.

Where the bitrate presets come from

  • Nextbase 322GW. Nextbase’s page says 32 GB gives 2 hours of footage, 64 GB gives 4 hours and 128 GB gives up to 8 hours [1]. Each of those works out to 16 GB an hour, which is about 35.6 Mbps. That is our arithmetic from Nextbase’s own claim, not a measured bitrate. Nextbase’s page does not say how the times depend on recording settings, and it gives 1080p at 60 fps in its specification table but 30 fps in its text [1].
  • Nexar’s suggested minimums. Nexar, a dash cam maker, suggests 12 to 15 Mbps for clean 1080p, 25 to 30 Mbps for 1440p and 50 to 60 Mbps for 4K. It says artefacts become visible below about 10 Mbps for 1080p [3]. This is one maker’s view and the figures are minimums for quality, not the bitrate your camera actually uses.
  • Your camera. If your manual or the camera’s settings give a bitrate, use that. It will be more accurate than any preset.

What the calculator cannot tell you

  • Real bitrate varies. Cameras may not record at a fixed rate, and the figures above are not measured values for any model.
  • Codec. Nexar says H.265 reaches equivalent quality at roughly half the bitrate of H.264 [3]. Enter your camera’s own rate rather than adjusting for this.
  • Parking mode and loop settings. Road Angel says the Halo Pro switches to time-lapse after 15 minutes of inactivity [2], which records far less than normal driving. The calculator treats all recording as continuous.
  • Card limits. Road Angel lists up to 128 GB, Class 10 for the Halo Pro, says high-endurance cards are preferred for loop recording and does not give recording times per card size [2]. The SD Association’s table says SDXC covers cards above 32 GB through 2 TB [4], but your camera may support less.
  • Usable space. A card’s label and the space your device shows can differ. The reserve box lets you allow for that.

Sources

  1. 322GW Dash Cam, Nextbase (European site), nextbase.eu. The page shows no date. Checked 19 October 2026.
  2. Halo Pro Front and Rear Dash Cam, Road Angel, roadangelgroup.com. The page shows no date. Checked 19 October 2026.
  3. Dash Cam Bitrate vs. Resolution: Why Higher Numbers Aren’t Always Better, Nexar (a dash cam maker). Updated 2 April 2026, getnexar.com. Checked 19 October 2026.
  4. Capacity (SD/SDHC/SDXC/SDUC), SD Association, sdcard.org. The page shows no date. Checked 19 October 2026.